Automatic gun charger



17952 E. c. BUNNELL AUTOMATIC GUN CHARGER l2 Sheets-Sheet 1 Filed June24, 1947 INVENTOR. a/z' CEZWMK fi au March 25, 1952 E. c. BUNNELLAUTOMATIC GUN CHARGER l2 Sheets-Sheet 2 Filed June 24, 1947 INVENTOR. I5% Cfizmneef- March 25, 1952 E. c. BUNNELL AUTOMATIC GUN CHARGER 12Sheets-Sheet 3 Filed June 24, 1947 w INVENTOR.

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AUTOMATIC GUN CHARGER Filed June 24, 1947 12 Sheets-Sheet 6 IN V EN TOR.

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March 25, 1952 E. c. BUNNELL 2,590,153

AUTOMATIC GUN CHARGER Filed June 24, 1947 12 Sheets-Sheet 8 I x "I///4/4 4 40/ 424 4/4 4 *7 M3 INVENTOR.

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March 25, 1952 E. c. BUNNELL AUTOMATIC GUN CHARGER l2 Sheets-Sheet 9Filed June 24, 1947 \Am NAN INVENTOR. (5.22% fb zz/z-lzz/f BY March 25,1952 E. c. BUNNELL 2,590,153

AUTOMATIC GUN CHARGER Filed June 24, 1947 12 Sheets-Sheet 10 INVENTOR. Iv

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March 25, 1952 E. c. BUNNELL AUTOMATIC GUN CHARGER l2 Shee'ts-Sheet 11Filed June 24, 1947 March 25, 1952 c, U N 2,590,153

- AUTOMATIC GUN CHARGER Filed June 24, 1947 12 Sheets-Sheet l2 INVENTOR.

- Patented Mar. 25, .1952

UNITED STATES ATENT FFE .QUTQMATIG GUN CHARGER Application June 24,1947, Serial No. 756,743

Autoyre l'lompany,

8 Claims.

This invention relates to automatic guns, commonly known as machineguns, for firing projectiles, and more particularly to guns of thatclass adapted, after once being set into operation, to continue to fireautomatically as long as the trigger is held in released position. v

In certain types of guns similar to that of the present invention. theparts have been so arranged that a substantial delay occurred betweenthe pressing of the trigger-release button and the firing of the firstround. In later types of drumment for aircraft, the trend has beentoward remotely. controlled firing of a single gun or a group thereof,whereby by means not pertinent here, several guns on a single aircraftmay be trained upon and are adapted to follow a single target. Inconnection with arrangements of this kind, automatic means have beenprovided whereby the gun, when traversing a course which will carry theprojectiles past a part of the aircraft, is made to cease firing and torecommence firing after the line of fire has passed to a. position wheredamage to the plane maynot occur. Under these circumstances it is highlyimportant that a minimum lagexist between the time the automatic cutoffis itself actuated and. the time when the gun responds. Whenconsideration is taken of the speed of the aircraft in straight flightand maneuvers, the rapidity with which the remotely controlled guns mustfollow an opposing aircraft, and the high rate of firing, it will beapparent that the lag aforesaid must be at an irreducible minimum.

Accordingly, one principal object of my invention is the provision ofmeans whereby the gun is fired from a closed bolt position as contrastedwith prior guns wherein firing is commenced with the bolt in openposition. Thus the time lag between, pressing of the trigger-releasebuttonand exit of the first round from the muzzle is reduced toanegligible degree and thereby the gun is better adapted to synchronizedfire as one of a plurality of.ggunsfor example, in aircraft, havingautomatic means controlling a plurality of guns trained on a commontarget.

Aircraft armament is generally located at positions' remote from theoperator, control of the trigger being through a contact closer andelectric circuit, by a Bowden wire, or equivalent means. Such remotelypositioned guns are generally charged, either initially or, in the eventof a. misfire or jam, during firing, by pneumatic mechanism associatedwith the breechblock to retract the bolt for feeding and chambering of around. It is highly desirable that the time elapsed between charging andthe beginning of firing be an absolute minimum, and for the reasonsheretofore outlined.

Still another object is to provide timing valve by the force of thegases of explosion and which actuates the feeder by release of thespring loading, thereby preventing jamming which may otherwise occurwith a positively operated feeding means. Thus variable pressure of thegases of explosion are not relied upon to actuate the feeder, but suchvariations are immaterial in loading the spring.

Another object is the provision of means operated by gases of explosionfor operating mechanism which unlocks the breechblock slides from closedbolt position to permit return of the slides and bolt to open-boltposition by blowback, which mechanism, being timed by the firing of apreceding cartridge, is more advantageously synchronized with themaximum effect of blowback action of the round.

In carrying out my invention in one form I provide a gun-chargingcylinder in which a piston is adapted to slide, the piston beingengageable with a projection on one of the breechblock slides, so thatupon admission of air against the piston, the pair of breechblock slidesand the bolt are retracted to open position, and a round may be fedtothe receiver and subsequently chambered upon release of the bolt byexhaust of the air from the cylinder. Such exhaust is arranged to occurdirectly to atmosphere by suitable valve means in order that the body ofexpressed air is not constrained to return through the air supply tubingand cook therefor. Air delivered to the charging cylinder actuatesapiston which loads a spring operating the feeding mechanism, and alsopasses through a timing valve to the charging cylinder, the actuation ofthe feeding piston preparing the timing valve so that it may be closedby pressure of the air delivered to the charging cylinder, and the gunis thereby held in charged position.

According to one aspect of my invention, the feeder-operating spring is,during automatic fire, loaded by gases of explosion of a round impingingon a piston to feed the next round, the pneumatic loading action and thegas-operated action being usable alternatively as pointed out. Inanother aspect my invention utilizes the same gases of ex- 3 against thelocked breechblock slides to unlock the same and permit the slides andbolt to be returned to open-bolt position by blowback of the round justfired.

In the drawings:

Figure 1 is a perspective view showing the lefthand side of the gun;

Fig. 2 is a perspective view showing the righthand side of the gun;

Figs. 3a and 3b constitute one view, being a lefthand side elevation ofthe gun, the view being broken into two parts, as indicated by thedotand-dash line, in order to fit the limitations of the sheet;

Fig. 4 is an enlarged fragmentary view taken in the same plane as Fig.3a and showing in cross section the forward portion of the boltunlocking "Fig. '7 is a cross-sectional view taken along the line 'I--'Iof Fig. 6b;

'Fig. 8 is a combined cross-sectional and lefthand elevational view ofthe gun taken substantially in a vertical plane through the axis of theFig. 9 is an exploded perspective view showing the bolt, the breechblockslides, the breechblock lock, the extractor and minor parts appurtenantthereto;

Fig. 10 is a cross-sectional view taken substantially on the line Ill-Iof Fig. 8;

Fig. 11 is a cross-sectional view taken substantially on the line I I II of Fig. 6b;

Fig. 12 is a cross-sectional view taken substantially on the line l2-I 2of Fig. b;

Fig. 13 is a cross-sectional view taken on the line I3-I3 Of Fig. 11;

Fig. 14 is a cross-sectional view taken on the line I4-I4 of Fig. 11;

Fig. 15 is a cross-sectional view taken substantially on the line I5I 5of Fig. 6a;

Fig. 16 is a cross-sectional view taken substantially on the line I6I 6of Fig. 6a;

Fig. 17 is a cross-sectional view taken on the line I'I-I'| of Fig. 6a;

Fig. 18 is a view in elevation and cross section showing the boltunlocking yoke and guide;

Fig. 19 is a detail, viewed from the front of the gun, of the boltcharging cylinder;

Fig. 20 is a cross-sectional view taken substan tially'on the line 20-20of Figs. 6a and 6b;

Fig; 21 is a cross-sectional view taken substantially on the line 2 I2 Iof Fig. 7;

Fig. 22 is a partial view, somewhat enlarged, of a portion of Fig. 5a toshow details of the pneumatic system;

Fig. 23 is a cross-sectional view taken axially of the bolt chargingcylinder and certain parts appurtenant thereto;

Fig. 24 is a view l00king toward the rear of the gun and showing thebolt charging cylinder, feeder operating cylinder, and certainconnections therebetween Fig. 25 is a cross-sectional view of a portionof one of the recoil cylinders;

' Fig. 26 is a detail showing a round assembled with its link and inrelation to the stripping cam;

Fig. 27 is a cross-sectional view on the line 2'I-2'I of Fig. 26;

Fig. 28 is a cross-sectional view on the line 28-28 of Fig. 26

Fig. 29 is a cross-sectional view taken on the line 2929 of Fig. 3b; and

Fig. 30 is a cross-sectional view taken on the line 3030 of Fig. 29.

In the several figures some parts have been shown broken away or omittedfor clarity.

Inasmuch as the entire assembly may be conveniently considered ascomposed of several cooperative sub-assemblies, the construction of thegun, one exemplification of which is shown and described, will bedetailed under appropriate subheads.

The gun mount The mounting for the gun as a whole comprises a cradle I0(Figs. 1, 2, and 10), preferably made of aluminum or magnesium alloy forlightness; narrower for the major portion of its length and wider towardthe front to receive the pair of recoil unit brackets I I supported bymeans of bolts I2 on upturned flanges I3 .at either side of the cradle.Flanges I3 also support the pair of slide bearings I4 (Fig. 3b) attachedthereto by means of bolts I5, there being one on either side of-the gunand disposed toward the rear thereof. Each bearing I4 comprises arectangular block havin a slot 23 for a purpose to be described. Thecradle I0 is provided with a plurality of apertures (not shown) by meansof which the cradle 'may be secured to a suitable support, which may befixed or mobile, and with a larger, sloping-sided, elongated aperture 9(Fig. 21) through which the spent cartridge casings may be ejected fromthe gun.

The receiver Forming the principal body portion of the gun, and housingthe bolt, the breechblock slides, the breechblock lock, and certainappurtenant parts, is an elongated, generally rectangular hollowreceiver 2|, preferably a steel casting having its inner side and upperwalls accurately machined for guiding the breechblock slides and bolt.At its two outer vertical side faces (Fig. 3b) the receiver 2I isprovided with a pair of elongated out.- standing ribs 22, each adaptedto slide in a slot 23 in the slide bearings I4 and forming part of themeans by which the recoiling portions of the gun are permitted to movewith respect to the cradle I0. Receiver 2| is provided in its upper wallwith an elongated slot 24 (Fig. 10) surmounted by a T-shaped slot 25 toaccommodate the receiver slide 26 to be described. I

Juxtaposed to the interior of the two side walls 21 and 28 of thereceiver 2| are the two receiver slides 3i (Figs. 6b and 21) attached tothe receiver 2I by means of cap screws 32 and held accurately inpredetermined position by means of flanges 33, each engaging a slot 34in the receiver. Each slide 3| is flanged inwardly as at 35 to supportthe bolt in its sliding movement, the upper outer edge of each flange 35being'chamfered as at 36 to provide clearance for the rounds duringchambering and extraction. The rear end of each receiver slide 3| isprovided with a cam formation to be further detailed.

The bolt, breechblock slides, and appurtenant parts of the assembledbolt and breechblock slides.

between the inner surface of the walls 21 an 28 of the receiver 2| BoltAll is provided on either side thereof with a longitudinal recess 44 forclearin the cartridge ejector to be described, and has a centralcircular ap rtur 45 (Fi 10) to rec ve. the fir n p and i n spri 1 (F n6.) The bolt i a o provided with a tr ns sel d spose Pad 48 to supportand guide the rear end of the bolt 4i upon the slides 3| (Fig. 9). 7

Ea h ehbl ck slid 43 and 4 .1 s u dee with an l n a a rture 5! hershreugh enclosing push rod 52 and compression spring 53 thereabout. the had 5 of he ush rod bei adapted to lie within a recess 54 (Fig. 52;) ofspherical segmental form out in the forward end of the aperture iii, therearward end 55 of each push rod 52 being adapted to pass through anaperture 576 in the lug 5 extending laterally from the bolt 4!. Therearward end of each spring 53, bears against the forward face of thelug El,

and the forward nd of the a d spri g bea s '64 in the bolt 41 and GI inthe slide .3., it being understood that the clearance. between the k 62and the apertures Si and 64 is such as to permit the slide 33 and boltll to ni-Qve freely longitudinally. with respect to. the key. Theright-hand end of the key 52, i. e., the end 55 coextensive in lengthwith the thickness, of ti le breechblock' slide 43, is somewhat narrowerthan the end secured in the breechblock slide 4.3a.

Passing through elongated apertures-1% (Fig.

'31)), one in each side wall of the. receiver- 'Z-i, is

the breechblock locking key 72 having a cross section of fiat-sided ovalform and locked transversely by means of a plate '13 (Fig. 10) securedat the bottom of the key by means of cap screws 74, the plate 13 beingof' the same width as. the interior of the receiver 2!. Key 52 is.provided at'its forward end with a recess l5. (Fig, 6b.) having ahorizontally disposed bottom wall it: and a rearwardly inclined wall Hfor a purpose to be described.

Pivoted upon a substantially semi-circular recess 8| coextensivewidthwise with the flanges, 82 of the bolt 4| is the breechblock lock 82(Fig. 9) having a substantially semi-circular forward end d3 to engagethe recess Bl, rearward locking SUI- faces 84 and 85, andcammingsurfaces 83 and 81, it being understood from Fig. 9 that, thebreechblock lock 82 is symmetrical abou-tthe vertical axial plane of thegun.

Each of the breechblock slides. i3; and 43:0. provided with a bottomrecess 91: adjacent. the rear end thereof, and of the, contour shown nFig. 9, there being a forward carnming; surface 92 and a rearward:cammingsurf-ace. 9.37.

Adapted to. lie. within a, suitable. recess 9,7; in

th bott m face of the bolt 4! is the extractor liil i 9) h i an a ert reH 2 t ansve se th reo where y the ex ractor i p ot n h pin 86 held inapertures I04 and the bolt 4!. The forward end Of, the extractor llllprovided with a claw H33 for engagement with the cartridge casing, theclaw being transversely arcuatc concentrically with the casing. At itsreal the extractor is provided with a longitudinal aperture iii-5 intowhich is inserted one end of the resilient rod H38 (Fig. 6b) supportedat its other end in a suitable aperture ii)? in the bottom of the bolt 4I.

The firing pin 45 (Fig. 9) is provided with a transverse recess [H ofslightly greater length (Fig. 7) than the key 62 whereby the pin 45 mayslide axially 9': predetermined short distance with respect to the key.The forward end of the pin 45. is provided with he substan ia y o c l.nos 112 adapted to project through an aperture H3 in the hardenedreplaceable bushing l [4 pressed into the forward face of the bolt iiiand flush therewith. the aperture H3 being suitably taper-ed tocorrespond to the taper of the nose H2 (Fig.

The bolt driving spring and buffer assembly For urging the bolt 4i andbreechblocl: slides 5,3 and 43a forwardly, there is provided the drivingspring ll (Figs; 'Z and 8) heretofore noted, the spring being supportedand guided upon the tube H5 secured at one end in the cap {IE5 at, therear of the gun. The tube H5. is supported at its, forward end on therod ill having an integral head HZ; guided Within the aperture 25 in thebolt 51. Spring 41 may be compressed freely within the aperture 4.5 andbears at. its icrward end against. the head 118, the latter in turnabutting the rear face of the firing pin 53. At. its rearward end thespring 4? bears against the inner wall lid of the cap H6.

Adapted to be removably associated with the receiver body 21! is thebuffer spring housing l2! engaged with the receiver 2! by means of avertically separable dovetail joint indicated generally at. M2, the,bulfer housing 121' and its associated parts being locked with respectto the receiver 2.1 by means of the manually operable pin lZIl slidablein the. housing i'2l. and normally urged into engagement, with anaperture (not shown), in the receiver by means of a spring (not shown).After the driving spring 41,, tube 115, and rod ll"! are removed fromthe receiver by unscrewing the capllfi from the housing [21, withdrawalof the pin I20 from its co-operating aperture permits the housing 52!and the parts enclosed thereby to. be dissociated from the receiver.,Eeassembly is obviously the reverse of the stehsiust outlined; There is,provided within the; housing ill a. bufier spring I23 having a washer lziabutting the front end thereof, thev spring I23. and washer I24. beingsecurely held within the. housing by means of the threaded sleeve I215.The rear end of the, bolt. 4| is pro vided with. an enlarged circularface I25 of sufiicient diameter to. bear against the washer I24 when,the bolt is, initsrearmost position;

The ejector assembly- 10 Carried; within ahousing l3i (Fig. 8) attachedll disposed at; each side of they bolt 41 and lying within the recesses44 of the bolt, there being an aperture MI in the slide to clear theejector assembly. Housing I3I is provided with a pair of apertures I35to receive the compression springs I36 adapted to urge the ejector I32in a clockwise sense and guided therein within apertures I31.Spring-retaining screws I38 are threadedly engaged in the housing I3I,the ejector I32, therefore, being constantly urged about its pivot andlimited in such forward movement by abutment against the edge of theaperture I4I of the housing I3I.

The barrel and barrel mounting The forward end of the receiver 2| isprovided with a pair of upstanding ears i I45, and the adapter I66 (tobe hereinafter described) is provided with a pair of laterally extendingears I46 (Figs. 6a and 20), each of said ears I45 and I46 having anaperture I41 therethrough to receive the studs I48. Extendingtransversely of and bearing against the rearward face of the aers I45 isan upper yoke I52 adapted to receive one end of the studs I48 threadedinto apertures I56 in the yoke I52, the studs being pinned by dowelsI49. The lower pair of studs I48 is similarly threaded into apertures IIin either end of a lower yoke I53 extending transverselyof the receiver2|, and abutting the front face I55 of a slot therein. I

At their forward extremities the studs I48 are threaded and engaged bythe nuts I54, the said nuts being provided with hexagonal depressions,not shown, whereby they may be engaged by a wrench.

Receiver 2I is provided with a cylindrical aperture I6I at its forwardend adapted to receive a corresponding cylindrical extension I62 of thebarrel I63 and whereby the barrel is accurately positioned axially ofthe receiver. An annular shim or spacer I64 is positioned intermediate ashoulder I65 of the barrel and the adjacent end of the receiver. Inorder to support thebarrel I63 with respect to the receiver 2 I, thereis provided a hollow adapter I66 having a flared portion I61 includingapertures (not shown) in alignment with the apertures I41 through whichthe studs I48 extend, the outer face of the portion I61 beingappropriately counterbored to receive the nuts I54. Thus it will beseenthat by means of the yokes I52, I53, studs I48, and nuts I54, theadapter I65 may be securely attached to the receiver 2|.

To permit disassembly of the barrel I63 from the adapter I68, both theadapter and barrel are engaged by means of circumferentially interruptedbuttress-thread sections generally indicated at HI, and of a commonconstruction sometimes used on breechblocks, whereby upon rotation ofthe barrel I63 a portion of a turn,

the interlocking threads are disengaged and the barrel. may bewithdrawn. To secure the barrel I63 against rotation, there is provideda dowel I12 adapted to engage a short peripheral slot 0 I13 entering aspace between two thread sections I1I, thus permitting the barrel to berotated for unlocking but to absorb the reaction due to the spin of thebullet.

' To preserve the peripherally locked relationship of the barrel I63with respect to the adapter I56, the barrel is provided with an axiallyextending slot I14 with which is adapted to engage the nose I15 of thebarrel latch I16 pivoted at I11 with respect to the adapter I66 and'tions of space) guided within a slot I18 therein. A projection I19limits inward movement of the nose I15 under urging of the compressionspring I82 intermediatethe front end of the latch I16 and the adapterI66. According, to unlock the barrel I63 from the adapter I66, the latchI16 is manually rotated clockwise, as seen in Fig. 6a,

to disengage the nose I15 from the slot I14. The barrel is thus free tobe rotated and unlocked as aforesaid. To facilitate graspingof thebarrel for manual removal thereof from the adapter I66, the same may beperiphrally knurled as at I92 (Fig. 2).

Barrel I63 comprises a breech or chamber I86 tapered, as indicated atI83 and I85, to receive the correspondingly tapered portions of the car-7 tridge employed with the gun, the cartridge, when chambered in 'thebreech I86, fitting snugly against the surfaces I83 and I85, and thegroove and rim thereof being positioned at the rear end of the breech,the latter being chamfered as indicated at I86 to permit free locationof the base of the cartridge, and also being provided with a radiallyextending recess I81 (Figs. 6a and 20) to receive the claw I63 of theextractor I6I.

The bore I06 of the barrel continues from the surface I83 to the muzzle(the latter being omitted in all of the" figures because of limita- Thebore is, as will be understood, of conventional construction, i. e.,spirally rifled to yield lands and grooves for imparting to theprojectile the appropriate rotary motion for true flight.

For supporting certain components to be hereinafter detailed, the barrelI63 is provided with a bracket 266 (Fig. 15), including a locking devicecomprising a hook I93 having an arcuate pad I94 adapted to engage thelower portion of the barrel I63, the hook continuing generally upwardlyin an extended cylindrical shank I95 guided in an aperture I98 in alaterally extending projection I91 of the bracket 266. Bracket 266 isprovided with another projection I98 disposed substantially above theprojection I91 and threadedly receiving the adjusting nut I99 in thecentral aperture 262 of which the shank I95 is guided at its upper end.Shank I95 is reduced to a flattened portion 263 through which passes thepin 264, and arranged to pivot thereon is the locking lever 265 (Fig.6a)Lever 265 is provided with a pair of camming surfaces 266 adapted tobear against the upper face of the nut I99, and includes a handle 261 bymeans of which the cam surfaces 208 may be brought into or out ofengagement with the nut I99, and the hook I93 accordingly operatedupwardly or downwardly to clamp or to releasev the bracket 266 withrespect to the barrel I63.

In order that accurate spacing between the cam surfaces 266 and the padI94 may be achieved, the nut I99 is, as hereinbefore mentioned,threadedly engaged with the projection I98 so that increase or decreasein said spacing may be efiected by rotating the nut I99 with respect tothe projection I98. To preserve the desired location of the nut I99, itslower terminus 2 is axially knurled, and adapted to engage with theserrations is the conical tip of the plunger detent 2I2 received in anaperture'2l3 in'the bracket 266. The detent is urged outwardly intocontact with the terminus 2II by means of a spring 2I4. Thus vibrationof the gun is inefiective to disturb the nut I99 and hence the lockedposition of the hook I93.

The recoil mechanism Referring now to Figs. 1, 2, a, 22, and 25, thereis'provided means for absorbing the recoil of the gun comprising a pairof recoil units 2I8, each including a cylinder 22I extending parallel tothe axis of the gun, one disposed on either side thereof and threadedlyengaged as at 222 with brackets 226 integral with and protrudinglaterally from the adapter I66. The brackets 223 are split at 222, theforward portion of the bracket being additionally split as at 225 topermit the same to be drawn together in a clamping action by means ofthe screws 226, thus to secure the cylinders 22I with respect to theadapter I66 after threaded assembly therewith.

Each cylinder 2'2I (Fig. 25) is internally threaded at 23I to receivethe annular adjusting prising a hollow cylinder, as shown, and termilhenating rearwardly in a bifurcation 24G. brackets I I include an upwardlydisposed ear 22'! (Fig. 3a) through an aperture 228 of which apertures229 in the bifurcation 25%) passes the pm 226. Caps 2I9 threaded uponthe nuts 232 serve to close the internal parts of the units 2I8.

The resilient structure 26-. is well known in this art and comprises twoalternated series of annular members of highly tempered spring steel ofshallow V-shaped cross section, as clearly indicated in Fig. 25,alternate members having the the apex of the V directed inwardly, andthe remaining members having the apex of the V directed outwardly. Thestructure thus constitutes a resilient assembly adapted to absorb energywith friction and to withstand the heavy recoil to which a gun of thetype herein disclosed is subjected. Adjustment in the tension of thestructures 23 5 is efiected by means of the nuts 23I'and 238. Inasmuchas the recoil units 2I6 are of a type frequently used in automatic guns,they form'no part of the present invention. Suflice it to state,however, that upon recoil of the gun, cylinders 225 being secured to theadapter I56 will be actuated rearwardly against the force of thestructures 235, the shock thereupon being transmitted resiliently to thecradle Hlthrough the support 239- and brackets I i.

The trigger assembly For initiating and interrupting firing, the gun iselectrically controlled through the medium of an electric switch orbutton actuated by the operator. Accessory controls may be used, as whenfiring is to be automatically interrupted as the gun is traversed withits trajectory intersecting some part of an aircraft and to avoid damagethereto. In such cases the firing is initiated by the operator, andcontrol is then transferred to automatic devices designed automaticallyto aim one or more guns at the target and to track the same. Cutouts areprovided for those guns whose trajectories are likely in some positionto intersect a part of the aircraft, and is thus auto- 10 maticallyinterrupted while the trajectory intersects such part.

In any such event, the electrical circuit to the gun includes a switchor switches, a source of current, and the solenoid 2 (Figs. 7 and 21)having an iron yoke 242 carried on the base 243, the electricalconductors being attached by means of a suitable female plug (not shown)engaging a male receptacle 254 attached to the yoke 242. To enablesimple detachment and attachment of the solenoid from and to the gun,there is provided a bracket 245 mounted by screws 246 to the receiver2I. One vertical edge 261 of 'the bracket 245 is beveled, as shown, toengage a correspondingly beveled rib 258 of the support 243. The latteris provided on its outer face with a pair of adjacent verticallydisposed beveled ribs 252 and 253 adapted to mate with a correspondinglychamfered shoe 254. Shoe 25 has a cir cular aperture 255 loosely fittinga swingable bolt 256 pivoted to the bracket 255 at 251. A flat spring26I backed by a washer 262 co-acts with a cam lever 263 pivoted at 264on the bolt 256, the handle 265 being bent at right angles, as shown,for a purpose to appear.

Thus to remove the solenoid, the handle 255 is swung counterclockwise(Fig. 21) to rotate the cam surface thereof away from the washer 262,thereby freeing the shoe 254 which may be disengaged from the ribs 252and 253. Consequently 'the bolt 256 and the parts supported thereon maybe swung away from the solenoid, the edge 22'! and rib 243 disengaged,whereupon the solenoid is freed for removal. Reassembly is ob viouslythe reverse of the foregoing, the handle 255 when in locked positionlying against the upper edge of the bracket 245. Accidental dislodgmentof the handle 265 is prevented by the presence of the wall of the feederhousing indicated thereover in Fig. 21 and to be hereinafter described.

An armature 2' is slidable Within the winding of the solenoid 2M, beingcylindrical in form and normally urged outwardly of the winding by acoiled compression spring 272. An aperture 213 axially of the armature2' receives the shank 272 of the trigger 215, the latter having a head21% fiat-oval in cross section and slidable within a correspondinglycontoured slot 21'! through the left-hand wall of the receiver 2|.

The bolt charging assembly In order to charge the gun initially or torecharge the same in the event of a jam or misfire,

zero is provided pneumatic means, including an elongated cylinder 29I(Fig. 10) formed in a suitable formed projection 292 disposedlongitudinally of the receiver 2i, approximatelyat midheight of theright-hand wall 21 and constituting in effect a protrusion of said wall.Adapted for reciprocating movement in the cylinder 29! and fittingsnugly therein is the bolt charging plunger 293 (Figs. 7 and 23),including a rear flange 294 and a front flange 295 disposed at each endof a body 296. Lying in a recess 291 peripherally of the flange 225 is aring packing are serving to seal the plunger with respect to thecylinder 29I and thus prevent air leakage beyond the forward face 299 ofthe flange 295.

A plug 3!! is snugly fitted within the rear end of the cylinder 29I,there being an axially disnosed channel 3 I 2 for clearing a lug on therighthand breechblock slide 43, as will be explained hereinafter. Tosecure the plug 3 I I with respect to the projection 292, there isprovided a cap nut and cylinder.

11 screw 3!3 (Fig. 19) passing through the wall of the projection andentering an aperture 3.!4 in the plug 3! Supported at its rear extremityin an aperture 3! 5 in the plug 3!! is the spring guiding and supportingtube Sit of suflicient length to extend .within the plunger 293 when thelatter is in extreme forward position. Surrounding the tube 3!S, anddisposed at its rear end in an aperture Si? in the plug 3!!, is the boltcharging plunger spring 3m, which at its forward end lies within anaperture 3l9 axially of the plunger and bears against the bottom of theaperture 389 of the plunger 263. The wall 2'? of the receiver 2! has aslot 320 for the greater portion of its length to provide clearance fora lug 312i (Fig. '7) extending laterally from the rear extremity of theright-hand breech-block slide 43.

Referring particularly to Fig. 23, the forward end of the cylinder 29Eis threaded at 323 to re ceive a correspondingly threaded adapter put32% having a shoulder 325 bearing against ring packing 326 whereby toseal the joint intermediate the Nut 324 is hollow and is threaded at 33!to receive the bolt 332 having a .blind axial aperture 333 and twodiametrically opposed apertures 334 therein. Fitted between the frontface of the adapter 324 and the head 335 of the bolt 3-32 is the quickrelease yalve body 335 (Figs. 23 and 24), there being an aperture 33'!therethrough snugly fitting the shank 338 of the bolt 332. Gaskets 339are provided intermediate the valve body 336 and the nut 324 and head335. It is to be noted that the aperture 331 is enlarged centrally for amajor part of its length to form a chamber 342 substantially coextensivewith the apertures 334.

That portion of the body 336 extending radially with respect to the axisof the cylinder 28! i generally cylindrical in form, and has acylindrical aperture 343 threaded to receive the cap nut 344, the jointintermediate the body 335 and nut 354 being sealedby means of the gasket345. The inner end of the nut 3 34 is reduced in dia deter and is offrusto-conical form, as shown in Fig. 23, the face of the truncationserving as a limit stop for parts now to be described.

Aperture 343 is reduce slightly in diameter the aperture 343. Tube 311is, in turn, connected to the air manifold shortly to be detailed.

Referring to Fig. 24, the body 336 is provided with a second laterallyextending boss 382 having a threaded aperture 353 to receive thethreaded nozzle 334, the aperture 383 continuing into a reduced portion386 in communication with the aperture 353. Nozzle 384 constitutes anair exhaust vent, it being noted in this respect that the aperture 386is in communication with that part of the aperture 343 intermediate thelower face of the piston 35! and floor 366.

The bolt unlocking assembly After each round is chambered, i. e., thrustby the bolt into the breech, the bolt 4! is locked for obturation bymeans of the breechblock lock 82 and the breechblock slides 43 and 43a,and in to join the cylindrical aperture 346 in which the quick releasevalve piston 35! is adapted to slide axially, the later beingpneumatically sealed with respect to the aperture by ring packing 352retained in the peripheral recess 353. Piston 35% is provided in itslower face with a recess 35% into which is pressed the annular valvedisc 355 having a central aperture v55, the outer corner of the recessbeing peened inwardly, as shown, to secure the disc in place. Alsoincluded in the piston 35! is an axial aperture 38! to receive thecompression spring 352' urging the ball check 363 against the port 364,the latter being sufliciently smaller in diameter than the aperture 36!to form a seat for the ball. An annular lip 36? projects upwardly fromthe floor 336 of the aperture 3 38 and is adapted to form a seat forthedisc 355. An aperture 3?! extends through the floor 365 and thuscommunicates with the chamber 342.

Body 336 is provided with a laterally extending boss 3'52 internallythreaded at 313 to receive the correspondingly threaded adapter 3'54. Tothe outer end of the latter are connected, by means of the nut 3'65, acompression bushing 3H; and tube 311, the opening of the tube communicating by means of apertures 378 and 3'59 with a manner subsequentlyto be pointed out. After firing, it becomes necessary to unlock thebreechblcck slides and bolt for discharge of the spent casing, and suchfunction is performed throughout automatic firing. For effecting suchpart of the cycle, there is provided timed pneumatic means now to bedetailed.

Disposed in axial alignment with the barrel N53 is the bolt unlockingplunger 40! (Fig. 611) comprising a tubular member having an integralbifurcated rear abutment including identical arms 432 (Fig. 16). Adaptedto be operated by the termini of the arms 402 is a pair of cylindricalrods 463 guided for axial movement in apertures 4G4 and 435 in theadapter !66 and receiver 2 respectively (Figs. 6a and 20) From Figs. 10and 20 it will be noted that approximately onequarter of the rear faceof the rods 493 is exposed within the chamber of the receiver 2!, andthat each face abuts the forward end of a breechblock slide 43 and 43a.

For guiding the rear end of the plunger 40! for reciprocating movement,the adapted I66 is provided with upstanding ears 4!! (Figs. 6a, 17, and18) defining a cylindrical aperture 4!2 into which is tightl fitted thecylindrical guide 4l3. Bolts 4l4 passing through apertures M5 in theears 4!! and engaging notches M6 in the guide 4l3 may be tightened togrip firmly the guide in the adapter I66, the ears 4!! yieldingsufficiently to afford clamping action. The guide M3 at its forward endis slidably fitted in the elongated bore 42! of the plunger 40!, theguide being slotted at 422' to engage a pin 423 secured in the plunger40!, thus to permit sliding movement of the plunger with respect to thefixed guide While maintaining the predetermined peripheral position ofthe plunger, i. e., with the arms 402 abutting the rods 403.

Slidable within the bore 42! is the piston 424 (Fig. 18) having anintegral piston rod 425 terminating forwardly in a reduced portion 426(Fig. 6a) which is peened over at its end 42'! to secure the guidebushing 428 slidable in an aperture 429 constituting a reduced portionof the bore 42!. Thus the piston 424 is guided at both of its ends forsmooth operation with respect to the plunger 40!. Interposed between theinner face of the piston 424 and a washer 432 is the compression spring433.

At its forward end the plunger 4!)! (Fig.4) is supported forreciprocating movement by means of the piston 434 comprising acylindrical head 435 and a shank 436, the latter "being pressed into thebore 42!. To reduce the mass of the piston 434, it may be drilled outas'at 43! and 438; and to prevent gas leakage, it may be provided with aplurality of peripheral grooves 4.4L

Supported in the gas port bracket 260 is the cylinder 4-82 having areduced portion 443 tightly fitted within the aperture 344 and locked inposition by a bolt 445 having a hexagonal head 445, the threads 44? ofthe bolt engaging corresponding threads in the cylinder 442; To providea passage between the interior of the cylinder M2 and the co-operativechambers of the bracket 20B and of the bore Hill, the bolt 445 has anaxial blind aperture 45! and a pair of radial apertures 452 and 453extending therefrom.

Bracket 250 is provided with passages 448 and 449 in communication withthe aperture 424, the passage 449 being in communication with a port 450extending through the wall of the barrel I63 to the bore Hi (Fig. 3a).

The feeder operating mechanism Feeding of the rounds to the receiver isachieved by pneumatic means now to be detailed. First there will bedescribed those elements of the feeder constituting directlyc0-operating parts of the pneumatically operated mecha nism, andthereafter the feeder proper, constituting a rapidly detachable part ofthe gun, will be detailed. The round-feeding mechanism per se will bedescribed only in so far as such description serves to explain theactuation thereof by those features of my invention claimed herein, thefeeder itself and certain elements co-operative therewith being theinvention of Roy S. Sanford, and described and claimed in hisapplication Serial No. 661,545, filed April 12, 1946, which applicationis assigned to the same assignee as the present application.

Rigidlysupported above the bolt unlocking plunger 40!, and paralleltherewith, is the feed operating cylinder 45! (Fig. 3a) comprising threeportions 462, 453, and 554 of successively reduced diameter terminatingforwardly in a portion 485 of greater diameter than portion 454, theprincipal support for the cylinder 45! being provided b a saddle 486integral therewith, as by weld ing- (Fig. 17), the downwardly extendingsides 46'! of the saddle each having a pair of apertures 468 engaged bythe bolts 4M aforesaid, whereby the cylinder is firmly attached to theadapter I66.

Threadedly secured in the rear open end of the cylinder portion 1352 isthe head gland 41! (Fig. 22), the holes 472 in the exposed peripherythereof being provided for locking wires (not shown) as is common inordnance for securing parts against loosening due to vibration.

the packing associated with the piston 48! pre- Adapted forreciprocating sliding movement within central apertures 493 and 494 inthe piston 48! and gland 41!, respectively, is the piston rod 495 (Fig.22), including a head 495 substantially of rectangular contour andhaving a cupshaped opening 491 therein (Fig. 20). At a positionsubstantially coincident with the juncture of portions 452 and 453, therod 495 is reduced in diameter, as indicated at 501, and is threaded toreceive the nut 502, the latter including a hexagonal head forengagement by a wrench and a reduced cylindrical portion 583 over whichis carried the flanged sleeve 5M. interposed between the shoulde definedby the interior of the two cylinder portions 453 and 54 (Fig. 5a) andthe flange of the sleeve 5% is the compression spring 5m. Forwardlybeyond the nut 552, the rod 495 is again reduced in diameter andcontinues (Fig. 3a) into a section 555 which is, in turn, reduced indiameter to form the terminal portion 555 threaded to receive a nut 551.Nut 55! serves to secure the piston 588 to the rod 495, said pistoncomprising a hollow body having a transverse wall 559 therein, anaperture 5 through the wall receiving the terminal portion 556.

Rod 495 is guided at its forward end in an aperture 512, in the cylinder513, which latter includes an aperture 5| 4, the latter communie eatingthrough a port 555 with the aperture 448. Cylinder 5I3 receives thepiston 558 for sliding movement therein, the latter being provided witha plurality of peripheral grooves 5l5 for preventing leakage. Thecylinder 5H3 is threadedly engaged in an aperture 515 in the bracket28!], and the said bracket carries an annular boss 5!! Gland All! isprovided with a shoulder .13 bearing against the ring packing 414 andterminates inwardly in an annular abutment surface 415.

Shims 415 serve to adjust the location of the piston rod for properfeeding. A plurality of apertures 41'! receive a spanner wrench forinsertion and removal of the gland 4H.

Reciprocably slidable within the portion 462 is the piston 48! having aperipheral recess 482 for retention of the packing 483 to seal thepiston with respect to the cylinder walL. 'Piston snugly fitted withinthe cylinder portion 485 whereby to support the forward end of thecylinder 45 I.

Turning now to Figs. 20, 22, and 2%, the cylindcr 45! is provided with ahousing 52! projecting from the right side thereof. An inclined passage522 therein is threaded to receive the hose connector 523, including ahead 524 having a peripheral groove 525, the gasket 526 sealing thejoint between the housing 52! and the connector 523. The latter is of acommon type to permit a mating hose terminal to be fitted against thehead 52 3 and a nozzle extending from the ter-.- minal to be inserted inthe aperture 521. A pair of manually operated tongs carried by theterminal may be engaged with the groove 525 to detachably secure thehose to the connector, whereby compressed air from a suitable source maybe fed to the pneumatically operated parts of the gun.

Passage 522 is reduced in diameter to continue into a passage 53! whichis in communication with the cylinder portion 452 at a point in theinner periphery thereof adjacent the plane of abutment of gland :31! andpiston 48L It will be noted that gland ll! and piston 48! are cham- 48I.has an annular abutment surface 484, and.

piston 48! and gland l'H are internally recessed at 485 and 485.,respectively, to receive packing comprising a seat 48?, packing leaves488, clamping ring 489, and snap ring retainers 39i received in grooves452, the gland ll! and pack ing associated therewith constituting astuffing box for the piston rod. soonto be described, While fered attheir outer abutting edges, as shown at .i-{Zand 413, respectively, toprovide a circumferential space therearound and with which pasage 53!communicates.

Threadedly inserted in another aperture 532 perpendicular to thecylinder is the timing valve body 533 (Fig. 22) comprising a head 5-34and a body portion 535, the latter snugly fita. reduce p r ion. Mini-theaper ure 53;

15 and sealed with respect thereto by ring packing 531 retained in theperipheral recess 538.

Body portion 535 is internally apertured to contain a spring-operatedball check valve 54! of a common type, e. g., the actuating plunger 542of the valve 54! extending slightly beyond the inner end of the body 535and abutting a projection 543 integral with" the timing valve striker544. The latter includes a peripheral flange 545 and a camming button546 guided within an aperture 541 in the wall of the cylinder 45!. Acompression spring 548 constantly urges the striker 544 inwardly tomaintain the button 546 against the periphery of the piston 48!.

Fluid communication between the aperture 536 and the space 55! isprovided by a plurality of radially disposed openings 552 (Figs; 22and'23) entrance to which is normally closed by ball check 54!. Forconnecting apertures '22 and 536 for flow therebetween, a by-passopening 553 is provided.

Reverting to Fig. 23, the tube 311 is connected by means of a nut 555and bushing 556 to the elbow 551 threadedly inserted at 558 in thehousing 52!, and is locked by jam nut 559. Housing 52! also has anaperture 56! in communication with the elbow 551 and the aperture 55!.

The feeder assembly The gun of the instant invention is intended toutilize the link-feeding principle wherein a plurality of rounds, eachcarried in an individual link, are assembled for convenient loading andfeeding of the rounds to the gun, the links being interconnected to forma flexible belt, as is well known in the art.

One form of link capable ofbeing used with the gun of my invention isshown and described in the copending application of Roy S. Sanford,Serial No. 628,207, filed November 13, 1945, now Patent No. 2,480,972,issued September 6., 1949, entitled Cartridge Belt Link, and assigned tothe same assignee as the present application.

Referring to Figs. 26, 2-7, and 28, there is represented, by way ofexample, a link 564 as disclosed in the copending Sanford applicationaforesaid, although it will be comprehended from what follows that linksof other constructions may be used, the desideratum being that such linkbe provided at least with resilient fingers for gripping a cartridge fordelivery thereof to the feeder and for preserving a predeterminedposition of the cartridge stripped therefrom, as will be hereinafterdetailed; and provided also with elements for engagement by the feedingand anti-backlash pawls and by the stripping cam, the said pawls and cambeing described fully hereinafter. Such link includes a rearsemi-cylindrical gripping portion 565, including tongues 5'66resiliently embracing the base end of the cartridge casing, and aforward gripping portion 561, including tongues 568 resilientlyembracing the forward part of the casing, both pairs of tonguesextending below the horizontally disposed axial plane of the cartridgewhereby the latter is gripped securely until it is desired to dislodgethe round from its link.

For interconnecting successive links, the same are provided with members51! and 512 adapted to interengage in a combined swiveling and hingingmovement whereby the required flexibility is imparted to the belt whileit passes from the magazineto the feeder. Inasmuch as'theinterconnection between links is" relatively.unimportant in so far as mypresentinvention is con--v cerned, further description of the detailsthereof will not be set forth. However, it is necessary that the link beprovided with an element adapted tobe engaged by the stripping cam to bedetailed. In the link illustrated, such member is shown at 513 andconstitutes a bridge intermediate the portions 565 and 512, the bridgebeing stiffened by corrugations 514 and so positioned with respect tothe cartridge as to define a space 515 for entrance of the nose of thestripping cam between the bridge and the case.

The cartridge or round 58! comprises a case L 582, including a slightlytapered principal portion 583, a base 584, and a peripheral extractorgroove 585, the latter being engageable by a lu or lugs (not shown)forming part of the link wherebythe cartridge is accurately locatedaxially with respect to thelink, and by means of which groove the casemay be extracted from the breech after firing, as will be described.Forwardly 'of-the portion 583 the case is reduced in diameter to form aneck 586, there being a steeply tapered portion 581 intermediate theneck and principal portion 583. The projectile 588 is of the usual formand determines the caliber of the gun, in this case 0.60 caliber,although obviously not limited thereto. Set into the center of the base584 is a primer (not shown) adapted to be struck by the firing pin 46,as is well understood in this art.

That portion of the feeding mechanism directly cooperative with thereceiver is carried on the receiver slide 26 heretofore referred to,which comprises an elongated flat plate having a plurality of laterallyextending flanges 59! (Figs. 5b and 21) arranged in pairs at each sidethereof and adapted to fit snugly in the T-slot 25, the latter beingrelieved as indicated at 592, whereby the slide 26 may be engaged anddisengaged from the receiver 2!. That is to say, the slide may be movedlongitudinally with respect to the receiver until flanges 59! underliethe notches 592, whereupon the slide may be lifted to detach the slideand its appurtenant parts from the gun. Movement of the slide todisengaging position is determined by the stop plate 593 attached to thetop of the receiver 2! by screws 594.

For locking the slide 26 securely in operative position there isprovided a detent 595 (Figs. 5b and 6b), including a handle 596engageable; by the fingers and pinned at 591 to a body 598, the latterhaving a peripheral flange 60! and an adjacent similar flange 602 ofslightly greater diameter, the body continuing to form a locking pin 603engageable in an aperture 604 through the top Wall of the receiver 2!.To afford clearance for the pin 603, the slide has an aperture,including acircular portion 599 and diametrically opposed rectangularwing portions 600, a key 606 fastened through the pin 603 being guidedwithin portions 600 thus to insure against rotation of the pin 603 andto maintain handle 598 in the predetermined position shown.

Enclosing the body 598 is the housing 601 having a hollow cylindricalbody portion and a flanged base 608 through which pass rivets 809 forsecuring the housing to the slide 25. Intermediate the cover 661 andflange 602 is the compression spring 6!! serving to urge the pin 603into engagement with the aperture 604. Hence, before the slide 26 may bedisengaged from the receiver as aforesaid, the handle 598 must be liftedagainst pressure of the spring 6!! to dis engage pin 603 from aperture604 whereupon the slide 26 is free to be moved rearwardly. KeyBOB

